As packaging density of microelectronic devices increases with technology developments, manufacturers are continually shrinking the sizes of microelectronic devices to satisfy increasing demand for smaller electronic devices, such as a three dimensional integrated circuit (3DIC) package, or package-on-package (PoP). Another trend in modern microelectronic devices is the increasing use of higher power consumption circuits, such as in a modern CPU chip or application processor. In order to accommodate the more densely packaged and the higher power consumption microelectronic devices, the heat dissipation property of a 3DIC package using through substrate vias (TSVs) or PoP technology needs be improved.
A heat sink, sometimes called a heat spreader, normally made of a higher thermal conductivity material such as copper has been used to fulfill the need for improving heat dissipation in 3DIC packages. In some instances, the 3DIC package includes at least one memory chip on a logic chip. Although copper, with its high thermal conductivity is a common solution for a lid of the heat spreader on an external surface of a 3DIC package, there exists a thermal constriction issue for dissipating heat between the memory chip and the logic chip.
The increased use of more densely packaged microelectronic devices, such as memory chips on logic chips, that lead to localized areas between chips or on the chip having relatively high heat generation (e.g., “hot spots”) to result in electrical performance degradation or even device failure.